Tumor Necrosis Factor-Like Weak Inducer of Apoptosis (TWEAK) Enhances Activation of STAT3/NLRC4 Inflammasome Signaling Axis through PKCδ in Astrocytes: Implications for Parkinson’s Disease

Abstract

Astrocytic dysfunction has been implicated in Parkinson’s disease (PD) pathogenesis. While the Tumor necrosis factor-like weak inducer of apoptosis (TWEAK)/Fn14 signaling axis is known to play a role in PD-like neuropathology, the molecular mechanisms that govern this process remain poorly understood. Herein, we show that TWEAK levels are elevated in PD serum compared to controls. Moreover, using both U373 human astrocyte cells and primary mouse astrocytes, we demonstrate that TWEAK induces mitochondrial oxidative stress as well as protein kinase C delta (PKCδ) and signal transducer and activator of transcription 3 (STAT3) activation, accompanied by NLRC4 inflammasome activation and upregulation and release of proinflammatory cytokines, including IL-1β, TNF-α, and IL-18. Mechanistically, TWEAK-induced PKCδ activation enhances the STAT3/NLRC4 signaling pathway and other proinflammatory mediators through a mitochondrial oxidative stress-dependent mechanism. We further show that PKCδ knockdown and mito-apocynin, a mitochondrial antioxidant, suppress TWEAK-induced proinflammatory NLRC4/STAT3 signaling and cellular oxidative stress response. Notably, we validated our in vitro findings in an MPTP mouse model of PD and in mice receiving intrastriatal administration of TWEAK. These results indicate that TWEAK is a key regulator of astroglial reactivity and illustrate a novel mechanism by which mitochondrial oxidative stress may influence dopaminergic neuronal survival in PD.

PKC Delta Activation Promotes Endoplasmic Reticulum Stress (ERS) and NLR Family Pyrin Domain-Containing 3 (NLRP3) Inflammasome Activation Subsequent to Asynuclein-Induced Microglial Activation: Involvement of Thioredoxin-Interacting Protein (TXNIP)/Thioredoxin (Trx) Redoxisome Pathway

“…SYBR Green qRT-PCR was performed on the harvested cells and tissues as described by Samidurai et al (2020). RNA was extracted using the TRIZOL reagent (Invitrogen, Carlsbad, CA, USA) as per the manufacturer's protocol.…”

“…Cells and tissue were lysed and homogenized using modified RIPA buffer and subjected to fluorescent immunoblotting as previously described (Gordon et al, 2016b;Samidurai et al, 2020). Normalized protein (30 µg) from each sample was loaded into their respective wells and separated using a 12% SDS-PAGE gel.…”

TNF-like weak inducer of apoptosis / nuclear factor κB axis feedback loop promotes spinal cord injury by inducing astrocyte activation

“…Then the culture dish was moved back and forth repeatedly. At last, cells were transfected with shTWEAK and shNF-κB for 48 hours [ 19 ].…”

“…Under normal conditions, relative low-level expression of TWEAK has been demonstrated in previous reports. However, relative expression of TWEAK was up-regulated under pathological conditions including in a neonatal hypoxic mouse model [ 18 , 19 ]. Moreover, recent studies had demonstrated that TWEAK and Fn14 were over-expressed in gliomas with a high level of NF-κB activation, suggesting that the TWEAK-NF-κB axis might serve as a potential target of neuroregulatory mechanisms in a context-specific manner [ 20 ].…”

Glial Cells and Brain Diseases: Inflammasomes as Relevant Pathological Entities

“…It was shown in primary mouse astrocytes and in the U373 cell line that the tumor necrosis factor-like weak inducer of apoptosis (TWEAK) treatment enhanced the activation of the Stat3/NLRC4 inflammasome signaling axis with the participation of PKCδ. TWEAK has been involved in PD-like neuropathology ( Samidurai et al, 2020 ). Given that Parkinsonian patients experience olfactory deficits, Zhang et al (2020a) treated mice with rotenone to simulate olfactory disturbances in PD.…”